Introduction: Diathermy is a new tool that could help subjects with chronic low back pain (CLBP), with no studies having compared it to other interventions already investigated such as dry needling.

Hypothesis: Diathermy is more effective than dry needling in improving pain intensity in the short term in subjects with CLBP.

Design: randomised controlled trial Methods: We will conduct a convenience sampling, with subjects receiving 2 treatment sessions with diathermy or dry needling, according to allocation. Subjects will be assessed at baseline, 1 week, 1 month and 3 months after treatment for pain intensity, disability, kinesiophobia and catastrophizing. Analysis of variance (ANOVA) and moderation analysis will be performed to evaluate the results, with 95% confidence intervals (CI).

A prospective longitudinal experimental randomised controlled trial study will be conducted from August 2022 to March 2023. The study will be conducted in accordance with the recommendations of the Consolidated Standards of Reporting Trials (CONSORT) statement,15 and in accordance with the Declaration of Helsinki.

Subjects were randomly assigned to one of the two intervention groups:

Diathermy. Diathermy treatment was applied using the TCaRe Power diathermy instrument (PRIM Physio©), using a capacitive system with an intensity of 50%, with slight variation depending on patient tolerance and 500khz. The therapy will be applied for 10 minutes on each side of the patient's lumbar region, who will be positioned in prone decubitus during the intervention.

The application will be active along with massage techniques. Dry needling. Dry needling is performed with a 4cm needle (APS Dry Needles®) on the most symptomatic side of the patient on palpation. To perform the technique, the patient is positioned in prone position on the couch. The physiotherapist palpates the lateral border of the lumbar iliocostalis muscle and performs the tapping technique in a latero-medial direction parallel to the stretcher.

The technique is performed by applying 12 incisions. After the application of the technique, ischaemic compression shall be performed for 1 minute.

Patients will complete a home exercise program

Inclusion Criteria:

• Age between 18 and 65 years.
• Chronic non-specific low back pain.
• Duration of pain of more than 6 weeks.

Exclusion Criteria:

• Neurological signs or symptoms.
• Radicular pain.
• Radiating pain below the knee.
• Belonephobia.
• Traumatic processes and/or surgeries in the lumbar region in the last year.
• Having received physiotherapy treatment in the last 3 months.
• Systemic diseases such as cancer, rheumatic diseases, neurological diseases.